LWG4098 views::adjacent<0> should reject non-forward ranges

Author: burblebee

source/ranges.tex

@@ -12241,7 +12241,8 @@
 \begin{itemize}
 \item
 \tcode{((void)E, auto(views::empty<tuple<>>))}
-if \tcode{N} is equal to \tcode{0},
+if \tcode{N} is equal to \tcode{0} and
+\tcode{decltype((E))} models \libconcept{forward_range},
 \item
 otherwise, \tcode{adjacent_view<views::all_t<decltype((E))>, N>(E)}.
 \end{itemize}
@@ -12874,7 +12875,8 @@
 a constant expression \tcode{N}:
 \begin{itemize}
 \item
-If \tcode{N} is equal to \tcode{0},
+If \tcode{N} is equal to \tcode{0} and
+\tcode{decltype((E))} models \libconcept{forward_range},
 \tcode{views::adjacent_transform<N>(E, F)} is expression-equivalent to
 \tcode{((void)E, views::zip_transform(F))},
 except that the evaluations of \tcode{E} and \tcode{F} are